Well I've finally gotten around to ordering a new trigger. I've bought replacement pins too just in case I lose any. I didn't opt for the springs since the place I'm buying from was sold out. In the meantime, in a fit of boredom, I've decided to disassemble the trigger assembly. Once I did that I figured I'd try to bend the top nub (the one that wasn't cut off completely but was instead attached by a millimeter of steel) back to its proper shape. I did that and reassembled the trigger assembly. Yup, that's what was causing the problem alright. Now the sear stays put in the tripping lever notch even when I press the selector button. It should be perfect with a new trigger. I'm hoping it gets here soon.